1. Field of the Invention
This invention relates to a method of making a picture display device, and more particularly to a method of making a color filter apparatus having a plurality of red filters, a plurality of green filters and a plurality of blue filters.
2. Description of the Prior Art
Generally, a picture display apparatus, such as a liquid crystal display (LCD), separates three primary color light signals, i.e., red(R), green(G) and blue(B) color light signals, from a light signal generated by a light source in order to display a color picture. Accordingly, the picture display apparatus is provided with a color filter apparatus in which a plurality of R filters for transmitting red light signals, a plurality of G filters for transmitting green light signals and a plurality of B filters for transmitting blue light signals are provided in each picture element (or pixel element).
In order to prevent deterioration of a picture displayed on the picture display apparatus and to prevent an undesired spreading or mixing of color, the R, G and B filters must be fabricated in such a manner to avoid being overlapped with respect to one another in the color filter apparatus.
As shown in FIG. 1(A) to FIG. 1(D), a color filter apparatus is fabricated by sequentially forming black matrix stripes 12, first filters 14 (i.e., R filters), second filters 16 (i.e., G filters) and third filters 18 (i.e., B filters) on the surface of a transparent glass substrate 10. Each of the first, second and third filters 14, 16 and 18 is formed by providing a corresponding color resist film so as to have a uniform thickness on the entire surface of the glass substrate 10 and then selectively exposing the resist film to light, and thereafter by developing the selectively exposed resist film.
In the method of fabricating the color filter apparatus in this manner, unremoved residual portions 15, 17 or 19 of the color resist films used for forming the respective filters 14, 16 and 18 remain on the periphery of the glass substrate 10. Thus, during the process of forming filters 14, 16 and 18, residual portions 15, 17 and 19 from each of the corresponding filters 14, 16 and 18, respectively, may remain on the surfaces of other filters and/or an area to be occupied by other filters. More specifically, when the first filter 14 is formed, the residual portion 15 of the first filter 14 is located on an area to be occupied by the second and third filters 16 and 18; when the second filter 16 is formed, a residual portion 17 of the second filter 16 is located on both surfaces of the first filter 14 and the area to be occupied by the third filter 18; and when the third filter 18 is formed, a residual portion 19 of the third filter 18 remains on the surfaces of the first and second filters 14 and 16.
Since the residual portions 15, 17 and 19 of the filters 14, 16, and 18 partially shut out a light signal transmitted via the filters, the transmissivity and the color revival rate in the filters 14, 16 and 18 is irregular. This results in a deterioration of a picture displayed on the display apparatus and a spreading or mixing of color in a picture display apparatus having the color filter apparatus. Moreover, in a liquid crystal display apparatus incorporating the color filter apparatus that seals the liquid crystal along with a thin film transistor substrate, the residual portions weaken an adhesion strength of the transparent electrodes to the black matrix stripes to thereby tear the sealed liquid crystal.